The present invention relates to the field of syringes, more particularly, syringe plungers.
Syringes typically include a barrel forming a hollow cylindrical body and a plunger located within the hollow cylindrical body. The plunger typically seals against the inner surface of the hollow cylindrical body. As a result, movement of the plunger within the hollow cylindrical body can be used to fill and/or dispense materials using the syringe.
A problem exists in removing air from between the plunger and material (e.g., a liquid or paste) within the barrel when the syringe is loaded with the material at a factory or by a user. For example, dispensing air with the material may make it difficult to accurately dispense a precise dosage, especially when the dosages are very small. Further, syringes that have trapped, compressed air tend to dispense material after pressure on the plunger is released due to the compressed air, resulting in weeping or oozing of the material.
Various plunger structures have been developed to vent this air when the plunger is inserted into the syringe barrel. Many of these structures do not, however, work well with materials having low viscosity because the structures allow the material to vent through the plunger away from the dispensing end of the syringe barrel. As a result, users have resorted to filling syringes under vacuum conditions, which is both expensive and time consuming. Further, some plunger structures only seal when pressure is applied to the plunger in the forward direction. Thus, air can be drawn back into the syringe barrel if movement of the plunger is reversed during use.
The present invention provides a self-venting movable seal and plunger assembly. The present invention also provides methods of using the assembly to dispense material. The assembly includes a movable seal and a plunger tip that allows the removal of an unwanted fluid from a cylindrical dispenser, e.g., syringe.
Among the advantages provided by the present invention is the ability to remove unwanted fluid from a cylindrical dispenser that is trapped between the material to be dispensed and the seal. The assembly can either be preassembled in the hollow cylindrical body and later filled by the user, or the user can first fill the body with the material and then insert the assembly into the hollow cylindrical body.
In one aspect, the present invention provides a method for venting trapped fluid out of a hollow cylindrical body while the hollow cylindrical body is being filled with a material by providing a hollow cylindrical body including a first opening and a second opening; a seal including a vent and a plunger tip pocket; and a plunger tip including at least one vent channel. The method further includes inserting the seal into the hollow cylindrical body, wherein a volume is defined within the hollow cylindrical body between the seal and the second opening of the hollow cylindrical body, and further wherein the volume contains a fluid. The method further includes filling the hollow cylindrical body with the material through the second opening of the hollow cylindrical body, wherein the fluid within the volume is vented through the vent of the seal as the material occupies the volume; inserting the plunger tip into the hollow cylindrical body via the first opening of the hollow cylindrical body; and seating the plunger tip in the plunger tip pocket of the seal, wherein the plunger tip occludes the vent when the plunger tip is seated in the plunger tip pocket, and further wherein fluid within the plunger tip pocket escapes through the at least one vent channel in the plunger tip while the plunger tip is being seated in the plunger tip pocket.
In another aspect, the present invention provides a method for venting trapped fluid out of a hollow cylindrical body while the hollow cylindrical body is being filled with a material by providing a hollow cylindrical body including a first opening and a second opening; a seal including a vent and a plunger tip pocket; and a plunger tip including at least one vent channel. The method further includes filling the hollow cylindrical body with the material; inserting the seal into the hollow cylindrical body, wherein a volume is defined within the hollow cylindrical body between the seal and the second opening of the hollow cylindrical body, wherein the volume contains a fluid, and further wherein the fluid within the volume is vented through the vent of the seal as the seal is inserted into the hollow cylindrical body. The method further includes inserting the plunger tip into the hollow cylindrical body through the first opening of the hollow cylindrical body; and seating the plunger tip into the plunger tip pocket of the seal, wherein the plunger tip occludes the vent when the plunger tip is seated in the plunger tip pocket, and further wherein fluid within the plunger tip pocket escapes through the at least one vent channel in the plunger tip while the plunger tip is being seated in the plunger tip pocket.
In another aspect, the present invention provides a self-venting movable seal and plunger assembly that includes a hollow cylindrical body including a first opening and a second opening; a movable seal including a plunger tip pocket, a first end and a second end, wherein a volume is defined within the hollow cylindrical body between the second end of the seal and the second opening of the hollow cylindrical body when the movable seal is located within the hollow cylindrical body, and a vent extending between the plunger tip pocket and the second end of the movable seal, wherein the plunger tip pocket is in fluid communication with the volume when the movable seal is located within the hollow cylindrical body; and a plunger tip including at least one vent channel, wherein the plunger tip is configured to seat within the plunger tip pocket of the movable seal, wherein the plunger tip occludes the vent in the movable seal when the plunger tip is seated within the plunger tip pocket, and further wherein fluid within the plunger tip pocket escapes through the at least one vent channel in the plunger tip as the plunger tip is seated in the plunger tip pocket.
In another aspect, the present inventions provides a self-venting movable seal and plunger assembly including a hollow cylindrical body including a first opening and a second opening; a movable seal including a plunger tip pocket, a first end and a second end, wherein a volume is defined within the hollow cylindrical body between the second end of the seal and the second opening of the hollow cylindrical body when the movable seal is located within the hollow cylindrical body, a vent extending between the plunger tip pocket and the second end of the movable seal, wherein the plunger tip pocket is in fluid communication with the volume when the movable seal is located within the hollow cylindrical body, and at least one pair of retaining plug receptacles; and a plunger tip including at least one vent channel, and at least one pair of retaining plugs, wherein the plunger tip is configured to seat within the plunger tip pocket of the movable seal, wherein the plunger tip occludes the vent in the movable seal when the plunger tip is seated within the plunger tip pocket, wherein fluid within the plunger tip pocket escapes through the at least one vent channel in the plunger tip as the plunger tip is seated in the plunger tip pocket, and further wherein the at least one pair of retaining plugs is configured to fit in the at least one pair of retaining plug receptacles of the movable seal.
These and other features and advantages of the invention may be described in more detail below in connection with some illustrative embodiments of the invention.